package nsusbloader.COM.NET;

import javafx.concurrent.Task;
import nsusbloader.NSLDataTypes.EFileStatus;
import nsusbloader.ModelControllers.LogPrinter;
import nsusbloader.NSLDataTypes.EModule;
import nsusbloader.NSLDataTypes.EMsgType;
import nsusbloader.COM.Helpers.NSSplitReader;

import java.io.*;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.*;

public class NETCommunications extends Task<Void> { // todo: thows IOException?

    private LogPrinter logPrinter;

    private String hostIP;
    private int hostPort;
    private String extras;

    private String switchIP;

    private HashMap<String, File> nspMap;
    private HashMap<String, Long> nspFileSizes;

    private ServerSocket serverSocket;

    private boolean isValid;
    private boolean doNotServeRequests;

    private OutputStream currSockOS;
    private PrintWriter currSockPW;
    /**
     * Simple constructor that everybody uses
     * */
    public NETCommunications(List<File> filesList, String switchIP, boolean doNotServeRequests, String hostIPaddr, String hostPortNum, String extras){
        this.doNotServeRequests = doNotServeRequests;
        if (doNotServeRequests)
            this.extras = extras;
        else
            this.extras = "";
        this.switchIP = switchIP;
        this.logPrinter = new LogPrinter(EModule.USB_NET_TRANSFERS);
        this.nspMap = new HashMap<>();
        this.nspFileSizes = new HashMap<>();
        // Filter and remove empty/incorrect split-files
        filesList.removeIf(f -> {
            if (f.isDirectory()){
                File[] subFiles = f.listFiles((file, name) -> name.matches("[0-9]{2}"));
                if (subFiles == null || subFiles.length == 0) {
                    logPrinter.print("NET: Removing empty folder: " + f.getName(), EMsgType.WARNING);
                    return true;
                }
                else {
                    Arrays.sort(subFiles, Comparator.comparingInt(file -> Integer.parseInt(file.getName())));

                    for (int i = subFiles.length - 2; i > 0 ; i--){
                        if (subFiles[i].length() < subFiles[i-1].length()) {
                            logPrinter.print("NET: Removing strange split file: "+f.getName()+
                                    "\n      (Chunk sizes of the split file are not the same, but has to be.)", EMsgType.WARNING);
                            return true;
                        }
                    }
                }
            }
            return false;
        });
        // Collect and encode NSP files list
        try {
            for (File nspFile : filesList)
                nspMap.put(URLEncoder.encode(nspFile.getName(), "UTF-8").replaceAll("\\+", "%20"), nspFile); // replace + to %20
        }
        catch (UnsupportedEncodingException uee){
            isValid = false;
            logPrinter.print("NET: Unsupported encoding for 'URLEncoder'. Internal issue you can't fix. Please report. Returned:\n\t"+uee.getMessage(), EMsgType.FAIL);
            //for (File nspFile : filesList)
            //    nspMap.put(nspFile.getName(), nspFile);
            close(EFileStatus.FAILED);
            return;
        }
        // Collect sizes since now we can have split-files support
        for (Map.Entry<String, File> entry : nspMap.entrySet()){
            File inFile = entry.getValue();
            long fSize = 0;
            if (inFile.isDirectory()){
                File[] subFiles = inFile.listFiles((file, name) -> name.matches("[0-9]{2}"));
                for (File subFile : subFiles)
                    fSize += subFile.length();
                nspFileSizes.put(entry.getKey(), fSize);
            }
            else
                nspFileSizes.put(entry.getKey(), inFile.length());
        }
        
        
        // Resolve IP
        if (hostIPaddr.isEmpty()) {
            DatagramSocket socket;
            try {                                        // todo: check other method if internet unavaliable
                socket = new DatagramSocket();
                socket.connect(InetAddress.getByName("8.8.8.8"), 10002);    // Google
                hostIP = socket.getLocalAddress().getHostAddress();
                socket.close();
            }
            catch (SocketException | UnknownHostException e) {
                logPrinter.print("NET: Can't get your computer IP using Google DNS server. Returned:\n\t"+e.getMessage(), EMsgType.INFO);
                try {
                    socket = new DatagramSocket();
                    socket.connect(InetAddress.getByName("193.0.14.129"), 10002);    // RIPE NCC
                    hostIP = socket.getLocalAddress().getHostAddress();
                    socket.close();
                }
                catch (SocketException | UnknownHostException e1) {
                    logPrinter.print("NET: Can't get your computer IP using RIPE NCC root server. Returned:\n\t"+e1.getMessage(), EMsgType.INFO);
                    try {
                        socket = new DatagramSocket();
                        socket.connect(InetAddress.getByName("people.com.cn"), 10002);    // Renmin Ribao
                        hostIP = socket.getLocalAddress().getHostAddress();
                        socket.close();
                    }
                    catch (SocketException | UnknownHostException e2) {
                        logPrinter.print("NET: Can't get your computer IP using Renmin Ribao server. Returned:\n\t"+e2.getMessage(), EMsgType.FAIL);
                        logPrinter.print("Try using 'Expert mode' and set IP manually.", EMsgType.INFO);
                        this.showAvalIpExamples();
                        isValid = false;
                        close(EFileStatus.FAILED);
                        return;
                    }
                }
            }
            // Say hello to MacOS Catalina
            // Also this part could be used instead of what we have above. One day it has to be tested on all platforms and fixed (replace code above).
            if (hostIP.equals("0.0.0.0")) {
                Socket scoketK;
                try {
                    scoketK = new Socket();
                    scoketK.connect(new InetSocketAddress("google.com", 80));
                    hostIP = scoketK.getLocalAddress().getHostAddress();
                    scoketK.close();
                } catch (Exception scoketKex) {
                    scoketKex.printStackTrace();
                    logPrinter.print("NET: Can't get your computer IP using Google server (InetSocketAddress). Returned:\n\t"+scoketKex.getMessage(), EMsgType.INFO);
                    try {
                        scoketK = new Socket();
                        scoketK.connect(new InetSocketAddress("people.com.cn", 80));
                        hostIP = scoketK.getLocalAddress().getHostAddress();
                        scoketK.close();
                    } catch (Exception scoketKexx) {
                        scoketKex.printStackTrace();
                        logPrinter.print("NET: Can't get your computer IP using Renmin Ribao server (InetSocketAddress). Returned:\n\t"+scoketKexx.getMessage(), EMsgType.FAIL);
                        logPrinter.print("Try using 'Expert mode' and set IP manually.", EMsgType.INFO);
                        this.showAvalIpExamples();
                        isValid = false;
                        close(EFileStatus.FAILED);
                        return;
                    }
                }
            }
            logPrinter.print("NET: Your IP detected as: " + hostIP, EMsgType.PASS);
        }
        else {
            this.hostIP = hostIPaddr;
            logPrinter.print("NET: Your IP defined as: " + hostIP, EMsgType.PASS);
        }

        // Get port
        if (! doNotServeRequests) {
            if (hostPortNum.isEmpty()) {
                Random portRandomizer = new Random();
                for (int i = 0; i < 5; i++) {
                    try {
                        this.hostPort = portRandomizer.nextInt(999) + 6000;
                        serverSocket = new ServerSocket(hostPort);  //System.out.println(serverSocket.getInetAddress()); 0.0.0.0
                        logPrinter.print("NET: Your port detected as: " + hostPort, EMsgType.PASS);
                        break;
                    }
                    catch (IOException ioe) {
                        if (i == 4) {
                            logPrinter.print("NET: Can't find good port", EMsgType.FAIL);
                            logPrinter.print("Try using 'Expert mode' and set port by yourself.", EMsgType.INFO);
                            isValid = false;
                            close(EFileStatus.FAILED);
                            return;
                        } else
                            logPrinter.print("NET: Can't use port " + hostPort + "\nLooking for another one.", EMsgType.WARNING);
                    }
                }
            } else {
                try {
                    this.hostPort = Integer.parseInt(hostPortNum);
                    serverSocket = new ServerSocket(hostPort);
                    logPrinter.print("NET: Using defined port number: " + hostPort, EMsgType.PASS);
                }
                catch (NumberFormatException nfe) { // Literally never happens.
                    logPrinter.print("NET: Can't use port defined in settings: " + hostPortNum + "\nIt's not a valid number!", EMsgType.FAIL);
                    isValid = false;
                    close(EFileStatus.FAILED);
                    return;
                }
                catch (IOException ioex){
                    logPrinter.print("NET: Can't use port defined in settings: " + hostPortNum + "\n\t"+ioex.getMessage(), EMsgType.FAIL);
                    isValid = false;
                    close(EFileStatus.FAILED);
                    return;
                }
            }
        }
        else {
            if (hostPortNum.isEmpty()){
                logPrinter.print("NET: Port must be defined if 'Don't serve requests' option selected!", EMsgType.FAIL);
                isValid = false;
                close(EFileStatus.FAILED);
                return;
            }
            try {
                 this.hostPort = Integer.parseInt(hostPortNum);
            }
            catch (NumberFormatException fex){
                logPrinter.print("NET: Can't use port defined in settings: " + hostPortNum + "\nIt's not a valid number!", EMsgType.WARNING);
                isValid = false;
                close(EFileStatus.FAILED);
                return;
            }
        }
        isValid = true;
    }
    /**
     * Show possible variants to log area
     * */
    private void showAvalIpExamples(){
        try {
            Enumeration<NetworkInterface> enumeration = NetworkInterface.getNetworkInterfaces();
            while (enumeration.hasMoreElements()) {
                NetworkInterface n = enumeration.nextElement();
                Enumeration<InetAddress> enumeration1 = n.getInetAddresses();
                while (enumeration1.hasMoreElements())
                    logPrinter.print("Check for: " + enumeration1.nextElement().getHostAddress(), EMsgType.INFO);
            }
        }
        catch (SocketException socketException) {     // Good block.
            logPrinter.print("Can't determine possible variants. Returned:\n\t"+socketException.getMessage(), EMsgType.FAIL);
        }
    }
    /**
     * Override cancel block to close connection by ourselves
     * */
    @Override
    protected void cancelled() {
        this.close(EFileStatus.UNKNOWN);
        super.cancelled();
    }

    @Override
    protected Void call() {
        if (!isValid | isCancelled())
            return null;
        logPrinter.print("\tStart chain", EMsgType.INFO);
        // Create string that we'll send to TF and which initiates chain 
        StringBuilder myStrBuilder;

        myStrBuilder = new StringBuilder();
        for (String fileNameEncoded : nspMap.keySet()) {
            myStrBuilder.append(hostIP);
            myStrBuilder.append(':');
            myStrBuilder.append(hostPort);
            myStrBuilder.append('/');
            myStrBuilder.append(extras);
            myStrBuilder.append(fileNameEncoded);
            myStrBuilder.append('\n');
        }

        byte[] nspListNames = myStrBuilder.toString().getBytes(StandardCharsets.UTF_8);                 // Follow the
        byte[] nspListSize = ByteBuffer.allocate(Integer.BYTES).putInt(nspListNames.length).array();    // defining order

        try {
            Socket handShakeSocket = new Socket(InetAddress.getByName(switchIP), 2000);
            OutputStream os = handShakeSocket.getOutputStream();

            os.write(nspListSize);
            os.write(nspListNames);
            os.flush();

            handShakeSocket.close();
        }
        catch (IOException uhe){
            logPrinter.print("NET: Unable to connect to NS and send files list. Returned:\n\t"+uhe.getMessage(), EMsgType.FAIL);
            close(EFileStatus.UNKNOWN);
            return null;
        }
        // Check if we should serve requests
        if (this.doNotServeRequests){
            logPrinter.print("NET: List of files transferred. Replies won't be served.", EMsgType.PASS);
            close(EFileStatus.UNKNOWN);
            return null;
        }
        logPrinter.print("NET: Initiation files list has been sent to NS.", EMsgType.PASS);

        // Go transfer
        Socket clientSocket;
        work_routine:
        while (true){
            try {
                clientSocket = serverSocket.accept();
                BufferedReader br = new BufferedReader(
                        new InputStreamReader(clientSocket.getInputStream())
                );

                currSockOS = clientSocket.getOutputStream();
                currSockPW = new PrintWriter(new OutputStreamWriter(currSockOS));

                String line;
                LinkedList<String> tcpPacket = new LinkedList<>();

                while ((line = br.readLine()) != null) {
                    //System.out.println(line);           // Debug
                    if (line.trim().isEmpty()) {          // If TCP packet is ended
                        if (handleRequest(tcpPacket))     // Proceed required things
                            break work_routine;
                        tcpPacket.clear();                // Clear data and wait for next TCP packet
                    }
                    else
                        tcpPacket.add(line);              // Otherwise collect data
                }
                //System.out.println("<Socket Closed>");
                // and reopen client sock
                clientSocket.close();
            }
            catch (IOException ioe){                      // If server socket closed, then client socket also closed.
                break;
            }
        }
        if ( ! isCancelled() )
            close(EFileStatus.UNKNOWN);
        return null;
    }

    // 200 206 400 (inv range) 404 416 (Range Not Satisfiable )
    /**
     * Handle requests
     * @return true if failed
     * */
    private boolean handleRequest(LinkedList<String> packet){
    //private boolean handleRequest(LinkedList<String> packet, OutputStreamWriter pw){
        File requestedFile;
        String reqFileName = packet.get(0).replaceAll("(^[A-z\\s]+/)|(\\s+?.*$)", "");

        if (! nspFileSizes.containsKey(reqFileName)){
            currSockPW.write(NETPacket.getCode404());
            currSockPW.flush();
            logPrinter.print("NET: File "+reqFileName+" doesn't exists or have 0 size. Returning 404", EMsgType.FAIL);
            return true;
        }

        long reqFileSize = nspFileSizes.get(reqFileName);
        requestedFile = nspMap.get(reqFileName);

        if (! requestedFile.exists() || reqFileSize == 0){   // well.. tell 404 if file exists with 0 length is against standard, but saves time
            currSockPW.write(NETPacket.getCode404());
            currSockPW.flush();
            logPrinter.print("NET: File "+requestedFile.getName()+" doesn't exists or have 0 size. Returning 404", EMsgType.FAIL);
            logPrinter.update(requestedFile, EFileStatus.FAILED);
            return true;
        }
        if (packet.get(0).startsWith("HEAD")){
            currSockPW.write(NETPacket.getCode200(reqFileSize));
            currSockPW.flush();
            logPrinter.print("NET: Replying for requested file: "+requestedFile.getName(), EMsgType.INFO);
            return false;
        }
        if (packet.get(0).startsWith("GET")) {
            for (String line: packet) {
                if (line.toLowerCase().startsWith("range")) {               //todo: fix
                    try {
                        String[] rangeStr = line.toLowerCase().replaceAll("^range:\\s+?bytes=", "").split("-", 2);
                        if (!rangeStr[0].isEmpty() && !rangeStr[1].isEmpty()) {      // If both ranges defined: Read requested
                                if (Long.parseLong(rangeStr[0]) > Long.parseLong(rangeStr[1])){ // If start bytes greater then end bytes
                                    currSockPW.write(NETPacket.getCode400());
                                    currSockPW.flush();
                                    logPrinter.print("NET: Requested range for "+requestedFile.getName()+" is incorrect. Returning 400", EMsgType.FAIL);
                                    logPrinter.update(requestedFile, EFileStatus.FAILED);
                                    return true;
                                }
                                if (writeToSocket(reqFileName, Long.parseLong(rangeStr[0]), Long.parseLong(rangeStr[1])))         // DO WRITE
                                    return true;

                        }
                        else if (!rangeStr[0].isEmpty()) {                           // If only START defined: Read all
                            if (writeToSocket(reqFileName, Long.parseLong(rangeStr[0]), reqFileSize))         // DO WRITE
                                return true;
                        }
                        else if (!rangeStr[1].isEmpty()) {                           // If only END defined: Try to read last 500 bytes
                            if (reqFileSize > 500){
                                if (writeToSocket(reqFileName, reqFileSize-500, reqFileSize))         // DO WRITE
                                    return true;
                            }
                            else {                                                  // If file smaller than 500 bytes
                                currSockPW.write(NETPacket.getCode416());
                                currSockPW.flush();
                                logPrinter.print("NET: File size requested for "+requestedFile.getName()+" while actual size of it: "+reqFileSize+". Returning 416", EMsgType.FAIL);
                                logPrinter.update(requestedFile, EFileStatus.FAILED);
                                return true;
                            }
                        }
                        else {
                            currSockPW.write(NETPacket.getCode400());                       // If Range not defined: like "Range: bytes=-"
                            currSockPW.flush();
                            logPrinter.print("NET: Requested range for "+requestedFile.getName()+" is incorrect (empty start & end). Returning 400", EMsgType.FAIL);
                            logPrinter.update(requestedFile, EFileStatus.FAILED);
                            return true;
                        }
                        break;
                    }
                    catch (NumberFormatException nfe){
                        currSockPW.write(NETPacket.getCode400());
                        currSockPW.flush();
                        logPrinter.print("NET: Requested range for "+requestedFile.getName()+" has incorrect format. Returning 400\n\t"+nfe.getMessage(), EMsgType.FAIL);
                        logPrinter.update(requestedFile, EFileStatus.FAILED);
                        return true;
                    }
                }
            }
        }
        return false;
    }
    /**
     * Send files.
     * */
    private boolean writeToSocket(String fileName, long start, long end){
        File reqFile = nspMap.get(fileName);
        // Inform
        logPrinter.print("NET: Responding to requested range: "+start+"-"+end, EMsgType.INFO);
        // Reply
        currSockPW.write(NETPacket.getCode206(nspFileSizes.get(fileName), start, end));
        currSockPW.flush();
        // Prepare transfer
        long count = end - start + 1;

        int readPice = 8388608;                     // = 8Mb
        byte[] byteBuf;
        long currentOffset = 0;

        try{
            //=================================  SPLIT FILE  ====================================
            if (reqFile.isDirectory()){
                NSSplitReader nsr = new NSSplitReader(reqFile, start);

                while (currentOffset < count){
                    if (isCancelled())
                        return true;
                    if ((currentOffset + readPice) >= count){
                        readPice = Math.toIntExact(count - currentOffset);
                    }
                    byteBuf = new byte[readPice];

                    if (nsr.read(byteBuf) != readPice){
                        logPrinter.print("NET: Reading of file stream suddenly ended.", EMsgType.FAIL);
                        return true;
                    }
                    currSockOS.write(byteBuf);
                    //-------/
                    logPrinter.updateProgress((currentOffset+readPice)/(count/100.0) / 100.0);
                    //-------/
                    currentOffset += readPice;
                }
                currSockOS.flush();         // TODO: check if this really needed.
                nsr.close();
            }
            //================================= REGULAR FILE ====================================
            else {
                BufferedInputStream bis = new BufferedInputStream(new FileInputStream(reqFile));

                if (bis.skip(start) != start){
                    logPrinter.print("NET: Unable to skip requested range.", EMsgType.FAIL);
                    logPrinter.update(reqFile, EFileStatus.FAILED);
                    return true;
                }

                while (currentOffset < count){
                    if (isCancelled())
                        return true;
                    if ((currentOffset + readPice) >= count){
                        readPice = Math.toIntExact(count - currentOffset);
                    }
                    byteBuf = new byte[readPice];

                    if (bis.read(byteBuf) != readPice){
                        logPrinter.print("NET: Reading of file stream suddenly ended.", EMsgType.FAIL);
                        return true;
                    }
                    currSockOS.write(byteBuf);
                    //-------/
                    logPrinter.updateProgress((currentOffset+readPice)/(count/100.0) / 100.0);
                    //-------/
                    currentOffset += readPice;
                }
                currSockOS.flush();         // TODO: check if this really needed.
                bis.close();
            }
            //-------/
            logPrinter.updateProgress(1.0);
            //-------/
        }
        catch (IOException | NullPointerException e){
            logPrinter.print("NET: File transmission failed. Returned:\n\t"+e.getMessage(), EMsgType.FAIL);
            logPrinter.update(reqFile, EFileStatus.FAILED);
            return true;
        }
        return false;
    }
    /**
     * Close when done
     * */
    private void close(EFileStatus status){
        if (isCancelled())
            logPrinter.print("NET: Interrupted by user.", EMsgType.INFO);
        try {
            if (serverSocket != null) {
                serverSocket.close();
                logPrinter.print("NET: Closing server socket.", EMsgType.PASS);
            }
        }
        catch (IOException ioe){
            logPrinter.print("NET: Closing server socket failed. Sometimes it's not an issue.", EMsgType.WARNING);
        }
        if (status != null) {
            logPrinter.update(nspMap, status);
        }
        logPrinter.print("\tEnd chain", EMsgType.INFO);
        logPrinter.close();
    }
}